I find I'm just much faster with paste. It does not require a tool
change for each component like hand soldering where I need to switch
between holding components in place and feeding solder.
Using paste it is more like an assembly line, first dispense all
paste, then place all parts, then solder all at once. I get very
efficient doing the same thing in a row.
I can set up hand soldering to be more efficient, for example by
tinning all first pins before starting to place any components,
then only placing parts reflowing that first pin, and as a last step
soldering all the other pins. But I'm still slower than using paste.
I'm prepared to race anyone wielding an iron ;-)
There are more minor reasons for me to use paste:
Positioning doesn't need to be accurate. Surface tension pulls parts in place.
Heating is even, some parts like ceramic capacitors are not specified
for the stresses of hand soldering.
Overall appearance is more like production, unless you put extra
effort into hand soldering.
ST
On Fri, Mar 12, 2010 at 12:55 PM, William Laakkonen
<
worldradiolabs@...> wrote:
> Hand Soldering any QFP requires:
>
> 1. Apply flux from mini-fluxer pen or similar
> 2. Position chip
> 3. tack solder opposite corners
> 4. glob solder across all pins, shorting most
> 5. lay a ∗good quality (E.G. M.G.Chemical) Solder Wick across the globbed
> solder on one side and drag the iron across the wick, lifting nearly all the
> solder, repeat this for other sides.
>
> It may be scary to consider globbing solder on a $20 chip- I've done it
> hundreds of times on QFPs now and have yet to lose a part.
>
> Elapsed time for an Atmega2560 (100 pin TQFP) about 5 minutes and no oven,
> paste, etc. Mind you I ∗have∗ used paste, hot air, solder mask.-, etc. I've
> used the above method successfully also with .35mm pitch parts since about
> 1992 and have done it hundreds of times. No special skill or tools needed,
> other than a good magnifier which you should have working with small items
> anyway. I'm not a young guy either, so I must work with the magnifier lamp.
>
> After soldering many thousands of SMDs, my conclusion is in most cases,
> solder paste is a wasted effort unless your in production. If you can see
> it, you can solder it with a (good) pen, solder, and wick. I use 0.015
> solder for 0603 and up. I use .022 or 0.035 for QFP or SOIC devices and wick
> up excess. I only see hot air and paste useful for things which you cannot
> reach with an iron (flexible kapton boards with blind connects, BGA, ETC)-
> and what hobbyist(s)) would use such parts unless they were free? I do see
> "homebrew" in the title, which to me evokes a sense of doing more with less
> and experimenting with new techniques.
>
> Loading and soldering is only one side of a homebrew_PCB.
>
> Regards,
>
> Bill
>
> On Fri, Mar 12, 2010 at 1:28 AM, Henry Liu <henryjliu@...> wrote:
>